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Patented Bee. 31, 1946
Henry R. Lee, Pitrnan, N. J., andv Edward T.
Howell, Wilmington, Del‘, assignors to E. I.
du'Pont de Nemours & Company, Wilmington,
Del}, a corporation of Delaware
No Drawing. .Application March 27, 1946,
Serial No. 657,612
2 Claims. (01. 260—'36_3)
vapor reaction‘ medium, much higher yields‘ of
This invention relates to‘ an improvement in the
process’ of the manufacture of dibenz'anthronyls,
andtmore particularly, to an improved process for
carrying- out the c'ondensationof benzanthrone
the Bz-l:Bz-l_’-dibenzanthronyl of a higher pu
rity are obtained than has heretofore‘ been pos
sible without reworking the unchanged benzan
throne, which offers dif?culties on a commercial
scale, The, alkyl sulfuric acids are preferably the
and its’ simple substitution derivatives to Bz-1:Bz
In the Conversion of benzanthrone to 32-1132
l’-dibenZanthronyl, the‘ condensation has here
methyl sulfuric acid and ethyl sulfuric acid.
When using these alkyl sulfuric acids, as little as
from 5 to '7 parts of the alkyl sulfuric acid may
tofore been carried out ,i'r‘iconcentrated sulfuric
acid by means" of an oxidizing agent such as man 10 be employedper part‘ of benzanthrone to be oxi
ganese dioxide, chromic acid, etc. The conver
dized‘.v Larger proportions may be employed, al
sion, as originally described in‘ German Patent
though the use of unnecessarily large amounts
431,774; was’ exceptionally low,'land a high per,
will, of course, make the process less economical.
centage of oxidation products were produced, It
The oxidizing agents employed are those which
was later found that; if the condensation was 15 have previously been used with sulfuric acid, such
carried out under more mild conditions and
as manganese dioxide and chromic acid an
stopped at a point where from 36% to 40% of
hydride. rl‘he amount of oxidizing agent to be‘
benzanthrone remaine'cd'l unchanged in the re
used Will be varied, depending upon the amount
action mass, a higher total- conversion to 332-1 :32
of solvent employed, although usually it will be
l"-diben'zant'hronyl could be obtained. This-prom 20 found that from 3 to 5 mols of manganese diox
ess, however, requires the recovery of the benzan~
ide (106% pure basis) per mol' of ben‘zanthrone
throne if comparatively high‘ yields of the
will give a satisfactory conversion of the benz
Bz-i:Bz-1’-dibenzanthronyl are to beob‘tained
anthrone to the dibenzanthronyl The oxidation
based on‘ the total’ benz'anthrone' employed‘;
is preferably carried out at temperatures of from‘
Irrespective of howrthe oxidation of the benz
ant-hrone has heretofore’ been carried out, side
25 —5° to 20° C., although lower or higher tempera
tures may be employed.
The alkyl sulfuric acid is preferably’ made as
a preliminary step in carrying out the oxidation
of the benzanthrone. In the preparation of the
react-ions inevitably take- place which produce
oxo-derivative's of both- benzanthrone and di-_
benzant-hrcnyl, and these remain as impurities
in the final product. On reduction of these oxo
derivatives, such‘ as with sulfurous acid, they are
alkyl sulfuric acid by the addition of anhydrous
alcohols to chlorosulfonic acid at low tempera
tures, there is usually present in the resulting
alkyl sulfuric acid a small “amount of sulfuric
in the main converted’ to h-ydroxy compounds
which will be referred to hereaftergenerally as
“oxy bodies.” A description of these o-xy bodies
acid, but it has been found that the presence
of this small amountrof sulfuric acid is not detri
mental in carrying. out the oxidation of the benze
may be‘ found in Examples 1 and 4 ‘of British
Patent 251,313. While some of the oXy bodies are‘
soluble in aqueous alkaline solutions, others, al
though apparently forming alkali metal salts, are
anthrone, While there is also present in the alkyl
sulfuric acid some residual hydrochloric acid, this ,
notlsu?i'ciently soluble to be removed by an al
kali'ne extraction, and it has'been found that cer
tain of the oxy derivatives'of Bz-1:B'z--1'-dibenz—
anthronyl were-notremoved by previous methods
of separation ‘andvwere’ therefore present with
the Bz-lzBz-ll-dibenz‘anthronyl as a mixture
which has heretofore ‘been mistaken for the
32-1 :Bz-l’ -dibenzanthronyl itself.
It is an object of the present invention to pro
vide an improved process for the preparation of
182-1 :Bz-1'-dibenzanthronyl and its simple mono
valent substitution derivatives, whereby higher
yields of the Bz-l:Bz-l’-dibenzanthrony1 are ob
tained and the amoLmt of oxy-bodies as impuri
ties is materially reduced.
We have now found that, where alkyl sulfuric
acids are used in place of sulfuric acid as the sol
can be largely eliminated by air-‘blowing or by
blowing an inert gas through the alkyl sulfuric
acid when formed. It has been found, however,
that the presence of small amounts of hydro
chloric acid‘ up to 0.75% does not materially af
feet the resulting oxidation reaction’.
The presence of excess alcohol or water in the
alkyl sulfuric acid, however, retards the subse
quent oxidation of the benzanthrone and gives
an unnecessarily high amount of unchanged benz
anthrone in the final product. For best results,
the alkyl sulfuric acid should be anhydrous and
free from alcohol.
For purposes of this invention, We do not wish
to be limited to any particular method of for
55 mation of the alkyl sulfuric acids.
2,413, 507
The following example is given to illustrate the
The parts used are by weight.
free and dried. The weight of this dried prod
uct, when compared with the original amount of
lbenzanthrone employed in the condensation, is
used as the yield of Bz-1:Bz-1'-dibenzanthronyl
1078 parts of chlorosulfonic acid are charged
into a closed enamel lined kettle fitted with agi
tator and cooling jacket. The charge is cooled
to —l0° C. and 302 parts of anhydrous methanol
obtained by the process involved.
When ethyl sulfuric acid is substituted for the
methyl sulfuric acid in the above example, a sim
ilar improvement in yields of a relatively pure
are slowly run in with cooling at such a rate that
Bz-lzBz - 1'-dibenzanthronyl is obtained.
the temperature does not exceed 0° C. Hydro 10 ethyl sulfuric acid employed may be produced
as follows:
chloric acid, which is copiously evolved, is vented
621 parts of chlorosulfonic acid are charged
o?. After all of the methano1 has been added,
into a closed enamel lined kettle ?tted with agi
the temperature of the mass is raised to from 20°
tator and cooling jacket. The charge is cooled
to'25° C. and dry air or an inert gas is blown
through until only traces of hydrochloric acid 15 to -10° C. and 245 parts of absolute ethyl alcohol
come out of the vent.
1000 parts of the above methyl sulfuric acid
are charged into a closed iron or steel kettle ?tted
- are slowly run in with agitation and cooling so
that the temperature does not exceed 0° C. The
hydrochloric acid gas evolved is vented off.
When all of the alcohol has been added, the mass
with agitator and cooling bath. 200 parts of
is allowed to warm to from 20° to 25° C. and is
puri?ed benzanthrone are charged in and the
blown with dry air until practically free from
solution is cooled to from '-5° to 0° C. 370 parts
hydrochloric acid.
of 81.6% manganese dioxide are added with cool
6 - methyl - benzonthrone, 6 ‘- chloro - benzan
ing at such a rate that the temperature does not
throne, or other halogen or methyl derivatives
exceed 5° C. After all of the manganese diox
ide has been added, the reaction mass is stirred 25 of benzanthrone which do not contain the halo
gen or methyl in the 2- or Bz-l-positions, can be
at from -5° to 0° C. until no further reaction
converted to the corresponding Bz-1:Bz-1’-di
takes place. This may require about 20 hours.
benzanthronyl in the manner illustrated in the
The reaction mass is discharged into 5000 parts
above example. Similar improvements in yield
of water containing 370 parts of sodium bisul?te.
400 parts of concentrated sulfuric acid are added 30 and purity of the resulting dibenzanthronyl are
and the slurry is heated to the boil. More so
The use of methyl or ethyl sulfuric acid not
dium bisul?te is added if an excess of sulfur di
only increases the yield of the desired Bz-lzBz
oxide is not detected. 5000 parts of cold water
1'-dibenzanthronyl but permits a material in
are added and the suspension is ?ltered off and
crease in the production of the dibenzanthronyl
washed acid-free. If not completely free from
per unit of equipment, for, while with the meth
manganese dioxide, the ?lter cake is milled and
yl and’ethyl sulfuric acid only from 5 to 7 parts
given an additional bisul?te treatment with sul
are required per part of benzanthrone, when us
furic acid, and is then ?ltered, washed acid-free
ing sulfuric acid as the solvent, optimum yields
and dried. Calculated to the ash-free basis, the
average analysis shows a 70.0% yield of Bz-l :Bz 40 of the dibenzanthronyl are obtained only when
at least 15 parts of sulfuric acid are employed per
part of benzanthrone.
A yield of 70% by this process is compared
We claim:
with a direct yield of from 40% to 55% of‘ B2
1. In the process for preparing Bz-l:Bz-1'-di
1:Bz-1'-dibenzanthronyl when the condensation
is carried out according to the processes of Ex 45 benzanthronyl and its halogen and methyl de
rivatives wherein condensation of the benzan
amples 2 or 3 of U. S. Patent 2,001,063, when the
yields are calculated on the basis of an acid re
throne compound is effected by means of an oxi
crystallization and puri?cation carried out as fol
Ten (10) parts of the crude Bz-1:Bz-1'-di
benzanthronyl, as obtained directly by the con
out the condensation of the benzanthrone com
50 pound in an alkyl sulfuric acid of the class con
densation as described above, are dissolved in 100
parts of 95% sulfuric acid at from 25° to 30° C.
28 parts of water are added at such a rate that
the temperature rises gradually to 100° C., and
the rate is then adjusted so that the rest of the
water is added at from 90° to ‘100° C. The mass
is allowed to cool to from 25° to 30° C. with agi
dizing agent, the step which comprises carrying
sisting of methyl sulfuric acid and ethyl sulfuric
acid, the reaction being carried out at temp-era
tures of from —-5° to 20° C.
2. In the process for preparing Bz-1:Bz-1’-di
benzanthronyl and its halogen and methyl deriv
atives wherein condensation of the benzanthrone
compound is effected by means of an oxidizing
agent, the step which comprises carrying out the
condensation of the benzanthrone compound with
tation. The microscope shows rod-like crystals
of a size su?cient to ?lter rapidly. The crystals 60 manganese dioxide in an alkyl sulfuric acid of
the class consisting of methyl sulfuric acid and
are ?ltered on a porous plate ?lter and are
ethyl sulfuric acid, the reaction being carried
washed with 100 parts of 75% sulfuric acid. The
out at temperatures of from -—5° to 20° C.
crystals are digested in water, ?ltered, washed
with water and digested in dilute caustic soda
solution. The slurry is ?ltered, washed alkali 65
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